The debate, which divides Mr Obama's most senior advisers, was thrown into stark relief by the leaked report of General Stanley McChrystal, the commander of US and allied forces in Afghanistan, warning that the war might be lost within a year without a further boost in troop strength and a major change in strategy to combat the spreading Taliban insurgency.
General McChrystal's bleak assessment coupled with Washington's frustration with the Afghan leader Hamid Karzai and the fraud-ridden election over which he presided, has reignited a rift between Vice-President Joseph Biden and Hillary Clinton, the Secretary of State, over how the war should be waged. It has also left Mr Obama facing a fateful choice: whether to go along with his generals and send yet more troops, or stand current policy on its head.
Spoken or unspoken, behind the debate lurks the shade of Vietnam. It emerged yesterday that The Washington Post, the first to report General McChrystal's devastating 66-page memorandum, agreed to delay publication by 24 hours, omitting elements relating to future tactics that the Pentagon and White House said might endanger American troops on the front lines in Afghanistan.
Bob Woodward, the paper's investigative reporter, who broke the story, compares the document to the secret history of the Vietnam war that caused a sensation when it was obtained in 1971 by The New York Times. The so-called Pentagon Papers "came out eight years too late," Mr Woodward says.
The stakes are now huge – so huge that the President barely mentioned Afghanistan in his address to the United Nations General Assembly yesterday. If Washington is perceived as opposing a further troop build-up, or leaning towards a reduction, then other countries in the coalition, where the eight-year-long war is even more unpopular than here, will rush for the exits.
Hitherto, the issue of the war in Afghanistan has seemed straightforward. In contrast to Iraq, Afghanistan has been the "good war" – a war of necessity, fought to make sure that a repeat of the 9/11 attacks, directed from Afghanistan by an al-Qa'ida sheltered by the Taliban, would never occur again.
Underlining this reinvigorated commitment, Mr Obama authorised an increase in US strength in Afghanistan to 68,000 by the end of the year, and named General McChrystal, previously in charge of US special forces, as his new commander on the ground. But the latter's recommendation of a boost of 30,000 to 40,000 confronts this president with a dilemma akin to that facing his predecessor over Iraq three years ago: to surge or not to surge? And views within the administration differ sharply.
Essentially the choice, in strategic jargon, is between counter-terrorism and counter-insurgency. The latter, implying a broad war against the Taliban to prevent it returning to power, seems to be what General McChrystal has in mind, and has long been backed by Mrs Clinton. Only this week, she had scathing words for those who argued that al-Qa'ida was no longer a factor in Afghanistan. "If Afghanistan is taken over again by the Taliban, I can't tell you how fast al-Qa'ida would be back."
The Vice-President, on the other hand, wants a narrower focus on al-Qa'ida itself, both in Afghanistan and Pakistan, where security forces have scored some important recent successes against the terrorist organisation and its Taliban allies. Under this approach, the US would require fewer forces in the field.
Instead of trying to protect the general population from the Taliban and operating a "hearts and minds" policy to win over civilian support, it would concentrate on targeted strikes on al-Qa'ida operatives, relying on umnanned drones, missile attacks and the special forces where General McChrystal is an expert. Simultaneously the training of Afghan government forces would be speeded up.
A third faction advocates a compromise, either scaling back the requested troop increase, or even starting to reverse it, while at the same time ensuring that the country does not collapse into chaos.
The White House and Pentagon are now studying the report, and it will be "weeks" before a decision is made, administration officials say. But Mr Obama, once so trenchant on the subject, is now hedging his bets. All options are on the table, he indicated during his blitz of the Sunday talk shows last weekend. "The first question is, are we doing the right thing?" he told CNN.
As it is, public support for the conflict is dropping sharply, too. According to a Wall Street Journal/NBC poll yesterday, 59 per cent of those surveyed were now "less confident" that the US could achieve a successful end to the war. More than half opposed an increase in American forces, while a third wanted an immediate pullout.
This growing pessimism is visible on Capitol Hill, too. Earlier this month, Nancy Pelosi, the Speaker of the House of Representatives, warned that neither Capitol Hill nor ordinary voters are in the mood for sending more soldiers to a war that has already taken almost 900 American lives – and 51 in August alone. Then Michigan's Carl Levin, chairman of the powerful Senate Armed Services Committee, declared that the US should send no more troops before a "surge" in Afghan security forces. But as even Pentagon officials concede, training Afghan forces up to the required standard of competence – not to mention loyalty – will be even more difficult than it was in Iraq.
Complicating matters further, Congressional leaders are now demanding a personal accounting from General McChrystal on how the war is going. For the moment Robert Gates, the Defense Secretary, has resisted the pressure, insisting the commander will only appear on Capitol Hill when a new policy has been decided. But if US casualties continue to grow, he may have little choice in the matter. In the meantime, Mr Obama is increasingly in a corner.
As Republicans constantly remind him, for the US to wind down its commitment would send a message of weakness and inconsistency to friends and foes alike. But to press on with a long, inconclusive war in a distant corner of Asia carries well-known and equal perils.
Once again, events are bearing out the famous aphorism of Mark Twain, that "while history doesn't repeat itself, it rhymes".
What would happen if he changed course now?
Joel Brinkley, US foreign correspondent, author, and academic
For most Americans now, Vietnam isn't a particularly powerful image. But policy- makers in charge now had some sort of role in Vietnam; and in Congress the lessons of recent history lay pretty heavily. I'm not sure America is at breaking point, but it does seem as if there is a heated discussion within the administration. Obama is a realist. He inherited this war and he proffered an approach that would reprioritise Afghanistan. But I think he's realised that it's probably too late.
Julian Thompson, Ex-Marines commander
The problem with switching to countering al-Qa'ida will be Pakistan, who will say: thank you, but we're not all that keen on having you guys operating in our patch. Perhaps if you're the US government you say you don't care, but that makes it much more difficult to sell. In a sense we're back to where we were in 2001. You can pour in more troops, but you have no guarantee of success. But I honestly don't see it as being parallel to Vietnam. In that situation, America was alone. Here, one of the most crucial things is for them to persuade Nato to share the load.
Karin von Hippel, Post-conflict expert
I think ultimately they'll give McChrystal what he needs – he's their man. But first they will have a debate. Before Iraq we didn't have a public debate, and Obama's very conscious of repeating that mistake. He knows he needs to regain waning support. Don't forget that this approach is basically what Obama said would happen in March, when he was trying to dampen expectations – and at the same time on the ground things were ratcheting up. At the moment, there's confusion out there.
Tim Cross, Major General (Retired)
The question is, what is the strategic intention in Afghanistan? Is it to enable the emergence of a democratic and stable nation? If that has been the intent, then this would be a serious change. It suggests that our intent is purely to deal with a perceived terrorist threat – but I'm not convinced that is right. So far, the UK has emphasised a comprehensive approach, using our non-military as well as military capability. And if Obama's approach changes, the UK would have to rethink its commitment.
(Source: The Independent, September 24, 2009)